This invention relates to high frequency transistor test fixtures used in testing RF transistors in microwave frequencies (see ref. 1, 2). Active RF components (transistors—DUT) need to be thoroughly tested at the operation frequencies before used in amplifier and other circuit designs. “Load pull” and “Source pull” (see ref. 3) are test methods which use impedance tuners to systematically characterize the DUTs under various load and source impedance conditions. Load pull or source pull are automated measurement techniques used to measure Gain, Power, Efficiency and other characteristics of the DUT, employing, beyond source and load impedance tuners, also other test equipment, such as signal sources, directional couplers, test fixtures to house the DUT and input and output power meters (FIG. 1), see ref. 3. Typical test fixtures used are based on micro-strip (FIG. 2) or coaxial (FIG. 3) transmission line structure.
Microstrip test fixtures (FIG. 2) include grounded input (22, 213) and output (28, 215) body sections and a DUT INSERT (214). The DUT (210) is mounted on the INSERT (214) using screws (26) or other securing mechanism. The fixture has input (20) and output (27) connectors and microstrip lines (29, 212) between the connectors. The microstrip lines comprise a dielectric layer on which a thin copper conductor layer is etched using photolithographic process. The DUT (210) package has leads (24, 211) which can be soldered or pressed on the microstrip (29, 212). A coaxial test fixture (FIG. 3) has two slabline sections made of the blocks (25), the cover (10) and the center conductors (31) which lead from the coaxial connectors, which are mounted on the vertical walls (11), to the DUT, which is mounted on the INSERT (21) using vertical studs or screws. The DUT leads are inserted in slots of the center conductors.